Mechanism of the metal–insulator–metal capacitance drift for advanced mixed-signal copper process device Original Research Article

The metal–insulator–metal (MIM) capacitors integrated in the 0.1 μm ultra-large-scale integrated device with various plasma treatments on TaNx plates were fabricated and investigated. The results showed that the capacitance drift in the MIM structure, TaNx/SiO2/TaNx, was due to the penetration of tantalum and the thinner thickness of oxide. Compared to the non-plasma-treated MIM capacitor, the root-mean-square (RMS) roughness of the TaNx surface exhibited a significant reduction after nitrous oxide and silane plasma treatments. Transmission electron microscopy (TEM) observation and secondary ion mass spectrometry (SIMS) analysis showed that a thin amorphous layer was formed at the TaNx/SiO2 interface after plasma treatments. The silane plasma treatment yielded comparable resistivity of TaNx and greatly suppressed the drift of the MIM capacitance.